Philopotamus montanus

I found this on the path just outside the door of the cottage we were holidaying in, during the daytime, not looking very healthy. It looked superficially similar to various members of the family Polycentropodidae, but I suspected it might be something else. The pattern of spots seemed different, and indeed Wallace, Wallace & Flint refer to this: "Philopotamus has the yellow spots of various sizes across the wing and although some may be in rows there are dark marks interspersed irregularly and the yellow spots are generally larger than those of the polycentropodids." On closer examination at home, the forelegs lacked the third spur and it clearly had ocelli.

The forewing venation was generally easier to see than it often is on polycentropodids, although the cross veins closing the discal and median cells were colourless so relatively difficult to make out. I did not immediately find it easy to make out the pale U-shaped area on segment IX referred to in Barnard & Ross, though this became slightyly easier after clearing the abdomen. I also compared the ventral, lateral and dorsal images at the ever-helpful Trichoptera fennoscandinavica website. This individual had a distinct pointed projection emerging from the midline of sternite VII, and a pale triangular area apical to this on the same sternite. I don't recall seeing that on other species before, so I wonder if this is also useful for the ID?

female Philopotamus montanusshowing wings, ocelli (from front and side), uncleared abdomen from side (2 views) and below (2 views), cleared abbdomen from below (2 views including sternite VII), above and side, Porthgwarra (Cornwall, UK), 15th October 2026

Although common across much of the north and west of the country, this species does not occur in Norfolk so I don't have much experience of it. I have seen it once before in Cornwall. I would have identified this using Barnard & Ross though I didn't record its sex so may not have checked the abdomen tip. I neglected to record how I found this but it was earlyish in the morning and I suspect it was netted in flight.

Philopotamus montanus, Lizard Point (Cornwall, UK), 8th April 2017